Ion sources may be used to propel ions toward a work piece, such as substrate or a sputter target, typically in the form of an ion beam. In an etching operation, the ions are intended to collide with and thereby etch away material on a work piece surface. In a sputtering operation, the ions collide with target material mounted on a base plate, causing atoms of the material to leave the target surface in a plume. Therefore, the plume may be directed to coat the surface of a substrate or other work piece with atoms of the target material.
During a sputtering operation, an ion beam sputters target material from the target surface, causing areas of the target material to thin or wear away. However, the sputtering rate over the surface of the target material is typically non-uniform, causing the target to wear away unevenly. When the ion beam sputters away enough target material to reach a certain depth in at least one area on the target, subsequent operation can risk sputtering all the way through the target material in that area to reach the base plate and/or an adhesive fixing the target material to the base plate. If the ion beam sputters all the way through the target material, the adhesive and/or the base plate material may be sputtered to the substrate, thereby contaminating the substrate. Accordingly, a sputtering operation on a particular target is typically terminated before any area of the target material is completely worn through, at which point the target is discarded or recycled. As such, the useful lifecycle of a target material is limited by the target area experiencing the maximum sputter rate.